The authors compare the concept of congestion with that of flow control and congestion control. A number of possible alternatives for congestion avoidance are identified. From these a few are selected for study. The c...
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The authors compare the concept of congestion with that of flow control and congestion control. A number of possible alternatives for congestion avoidance are identified. From these a few are selected for study. The criteria for selection and goals for these schemes are described. In particular, the authors wanted the scheme to be globally efficient, fair, dynamic, convergent, robust, distributed, configuration-independent, etc. They model the network and the user policies for congestion avoidance as a feedback control system. The key components of a generic congestion-avoidance scheme are congestion detection, congestion feedback, feedback selector, signal filter, decision function, and increase/decrease algorithms.< >
The partitioning of operating system services in a distributed system and its impact on performance are discussed. An examination is made of the tradeoff between partitioning a service at a higher layer, which could p...
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The partitioning of operating system services in a distributed system and its impact on performance are discussed. An examination is made of the tradeoff between partitioning a service at a higher layer, which could potentially result in greater computation at the server, and partitioning at a lower layer, which could result in less service-related computation at the server but may require more communication with the server. As a case study, the performance implications of providing alternate types of distributed mass storage services are considered, focusing on those partitionings that result in a file and a disk service. A detailed multiclass closed queuing network model of the remote service with users on workstations is used in the study.< >
In this paper, we study the performance characteristics of a client-server style distributed system by a queucing network model. The system being modeled was based on an experimental distributed system currently being...
作者：
BROWER, KSWALKER, KWKenneth S. Broweris a partner in Spectrum Associates Incorporated
Arlington Virginia a naval architecture firm which he founded in 1978. He graduated from the University of Michigan in 1965 with a B. S. degree in naval architecture. Mr. Brower has contributed to the design and construction of numerous merchant ships and warships the latter of which include the CG-47 Project Arapaho the FDL and DX projects and the NA TO frigate replacement DDGX and FFX projects as well as several frigates developed for foreign military sales. Since 1972 he has actively participated in the Naval Sea Systems Command's comparative naval architecture program. During this period Mr. Brower has contributed to or been the author of numerous widely distributed technical reports on international ship design practices. A member of ASNE Mr. Brower was a recipient of the ASNE “Jimmie” Hamilton Award for 1983 for the article “Seakeeping and Combat System Performance—An Operator's Assessment” which he coauthored. Kenneth W. Walkeris a naval architect with Spectrum Associates Incorporated
a firm which specializes in the development of ship design synthesis computer programs. He graduated from the Webb Institute of Naval Architecture in 1960 with a B.S. degree. Mr. Walker worked in the preliminary design division of the Naval Sea Systems Command and its precedent commands during the period between 1960 to 1977. He was employed primarily in conducting feasibility design studies and preliminary designs of naval ships. His work also included the development of subroutines for use in ship design synthesis computer programs under development and the documenting and flow charting of entire programs.
Naval ship design synthesis computer programs, the original development of which was pioneered by the U.S. Navy, are now used by the U.S. Navy to conduct feasibility design studies and to conduct reverse engineering a...
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Naval ship design synthesis computer programs, the original development of which was pioneered by the U.S. Navy, are now used by the U.S. Navy to conduct feasibility design studies and to conduct reverse engineering analyses of foreign ships. The use of these computer programs has substantially reduced the time and cost of conducting feasibility design trade-off studies and has allowed the ship designer to develop very accurate design solutions that can be effectively used as the basis for preliminary and contract design. The paper describes an interpolative technique for ship design which the authors have developed and incorporated in a variety of ship design synthesis computer programs, without any loss in the accuracy of the design solution. The interpolative technique short cuts the classic and time consuming design spiral approach to conducting ship design studies, which was incorporated in the original ship design computer programs. The interpolative technique also significantly reduces computer operating costs and provides the ship designer with the flexibility required to quickly study the performance and cost impact of using any number of innovative ship configurations. The paper describes programming techniques and ship design logic which allow a ship design computer program to be used to study the impact of using alternative ship design criteria and practices, including different types of hull forms and stability criteria. Also discussed are alternative ways that ship design parametric data can be developed for use in a ship design synthesis computer program. An example of a ship design study which was conducted using the interpolative technique is shown.
作者：
CAPT. JAMES KEHOE JR.KENNETH S. BROWEREDWARD N. COMSTOCKUSN (RET.)Captain James W. Kehoe
Jr. USN (Ret:.) is well known for his work in conducting comparative naval architecture studies of U.S. and foreign warships design practices for which he received the ASNE Gold Medal for 1981 and the Legion of Merit. He is currently a partner in Spectrum Associates Incorporated Arlington Virginia where he engaged in the feasibility and concept design of naval ships and in continuing his comparative engineering analyses of U.S. and foreign warships. Prior to his retirement from the U.S. Navy in 1982 his naval career involved sea duty aboard three destroyers and three aircraft carriers including command of the USSJohn R. Pierce(DD-753) and engineer officer of the USSWasp(CVS-18). Ashore he had duty at the Naval Sea Systems Command where he directed the Comparative Naval Architecture Program as an instructor in project managementin the Polaris missile projectand as a nuclear weapons officer. A frequent contributor to theNaval Engineers Journal
U.S. Naval Institute Proceedings and theInternational Defense Review he has published a number of articles on U.S. Soviet and other foreign design practices and the effects of design practices on ship size and cost. He has been a member of ASNE since 1974. Kenneth S. Brower:is a partner in Spectrum Associates Incorporated
Arlington Virginia which he founded in June 1978. He graduated from the University of Michigan in 1965 with a Bachelor's Degree in Naval Architecture. Mr. Brower has contributed to the design and construction of numerous merchant ships and warships the latter of which include the CG-47 Project Arapaho (in both cases as feasibility design manager) the FDL and DX projects and the new NATO Frigate Replacement for the 90s DDGX and FFX projects. He conceived and directed the development of several frigates and corvettes for foreign military sales. Mr. Brower directed the development of unique reverse engineering ship design computer models and the development of Spectrum Associates' own keel-up Ship Desi
作者：
KEHOE, JWBROWER, KSCOMSTOCK, ENCapt. James W. Kehoe
Jr. USN (Ret.):is well known for his work in conducting comparative naval architecture studies of U.S. and foreign warship design practices for which he received the ASNE GoldMedalfor 1981 and the Legion ofMerit. He is currently a partner in Spectrum Associates Incorporated Arlington Virginia where he is engaged in the feasibility and concept design of naval ships and in continuing his comparative engineering analyses of U.S. and foreign warships. Prior to his retirement from theU.S. Navyas a Captain in 1982 his naval career involved sea duty aboard three destroyers and three aircraft carriers including command of theUSS John R. Pierce (DD-753)and engineer officer of theUSS Wasp (CVS-18). Ashore he had duty at the Naval Sea Systems Command where he directed the Comparative Naval Architecture Program as an instructor in project managementin the Polaris missile projectand as a nuclear weapons officer. He holds a B.S. in mathematics from Stonehill College
Massachusetts (1952) and an MA in education from San Diego State College (1959). A frequent contributor to theNaval Engineers Journal U.S. Naval Institute Proceedings and theInternational Defense Review he has published a number of articles on U.S. Soviet and other foreign warship design practices and the effects of design practices on ship size and cost. Mr. Kenneth S. Brower:is a partner in Spectrum Associates Incorporated
Arlington Virginia which he founded in June 1978. He graduated from the University of Michigan in 1965 with a Bachelor's Degree in Naval Architecture. Mr. Brower has contributed to the design and construction of numerous merchant ships and warships the latter of which include theCG-47 projectArapaho theFDLand DX projects the new NATO Frigate Replacement for the 90's DDGX and FFX projects as well as several frigates developed for Foreign Military Sales. Since 1972 he has actively supported the Naval Sea Systems Command's Comparative Naval Architecture Proram. During this period Mr. Brower has cont
In a recent effort to improve our assessment of the Comparative seakeeping performance of existing U.S. N avy ships, a seakeeping questionnaire was distributed to the Commanding Officers of U.S. N avy frigates, destro...
In a recent effort to improve our assessment of the Comparative seakeeping performance of existing U.S. N avy ships, a seakeeping questionnaire was distributed to the Commanding Officers of U.S. N avy frigates, destroyers, and cruisers. The objectives were to determine, (1) the operational availability of existing weapons and sensors in relation to a ship's seakeeping performance, (2) the availability of ships to make full speed and to conduct sonar, helicopter, and replenishment-at-sea operations, (3) effects of a ship's seakeeping limitations on task force and convoy operation, and (4) realistic seakeeping design crteria for use in the design of new ships. The responses to the questionnaire indicated that frigates are severely limited in their availability to conduct ASW task force and convoy operations in the North Atlantic during the winter season because of seakeeping limitations on speed, hull sonar performance, and helicopter operations. The findings suggest that in the design of future ships we need to place emphasis on improving the seakeeping performance of ships in rough water, instead of just their speed and range in calm water. They indicate that the ASW capability of U.S. ships in high sea states would be enhanced by a towed acoustic sensor; an extended range ASW missile; active fin roll stabilizers; and a helicopter recovery assistance, securing and traverse (RAST) system. They also suggest that the question of the interaction of a ship's size and seakeeping characteristics with the choice of weapons and sensors requires careful attention in the design of future U.S. N avy ships.
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